lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Tue, 20 Jun 2017 12:27:42 +0200 From: Ingo Molnar <mingo@...nel.org> To: Daniel Axtens <dja@...ens.net> Cc: linux-kernel@...r.kernel.org, peterz@...radead.org, mingo@...hat.com, Konstantin Khlebnikov <khlebnikov@...dex-team.ru>, Ben Segall <bsegall@...gle.com>, Thomas Gleixner <tglx@...utronix.de> Subject: [PATCH] sched/debug: Fix SCHED_WARN_ON() to return a value on !CONFIG_SCHED_DEBUG as well * Daniel Axtens <dja@...ens.net> wrote: > If we set a next or last buddy for a se that is not on_rq, we will > end up taking a NULL pointer dereference in wakeup_preempt_entity > via pick_next_task_fair. > > Detect when we would be about to do that, throw a warning and > then refuse to actually set it. > > This has been suggested at least twice[0][1]: just do it. > > [0] https://marc.info/?l=linux-kernel&m=146651668921468&w=2 > [1] https://lkml.org/lkml/2016/6/16/663 > > Cc: Konstantin Khlebnikov <khlebnikov@...dex-team.ru> > Cc: Ben Segall <bsegall@...gle.com> > Cc: Peter Zijlstra <peterz@...radead.org> > Cc: Thomas Gleixner <tglx@...utronix.de> > Signed-off-by: Daniel Axtens <dja@...ens.net> > > --- > > I recently had to debug a problem with these (we hadn't backported > Konstantin's patches in this area) and this would have saved a lot > of time/pain. > > v2: use SCHED_WARN_ON to restrict when the test is run. This is a > macro for WARN_ON_ONCE, which is convenient. > --- > kernel/sched/fair.c | 10 ++++++++-- > 1 file changed, 8 insertions(+), 2 deletions(-) > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index d71109321841..44b94cfe02cb 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -6168,8 +6168,11 @@ static void set_last_buddy(struct sched_entity *se) > if (entity_is_task(se) && unlikely(task_of(se)->policy == SCHED_IDLE)) > return; > > - for_each_sched_entity(se) > + for_each_sched_entity(se) { > + if (SCHED_WARN_ON(!se->on_rq)) > + return; > cfs_rq_of(se)->last = se; > + } This won't build in the !CONFIG_SCHED_DEBUG case, because of the naive definition in sched.h: #define SCHED_WARN_ON(x) ((void)(x)) That should be changed to something like: #define SCHED_WARN_ON(x) ((void)(x)) I've applied the fix below. (untested at the moment) Thanks, Ingo ========================> >From 6d3aed3d8a0573d0a6eb1160ccd0a0713f4dbc2f Mon Sep 17 00:00:00 2001 From: Ingo Molnar <mingo@...nel.org> Date: Tue, 20 Jun 2017 12:24:42 +0200 Subject: [PATCH] sched/debug: Fix SCHED_WARN_ON() to return a value on !CONFIG_SCHED_DEBUG as well This definition of SCHED_WARN_ON(): #define SCHED_WARN_ON(x) ((void)(x)) is not fully compatible with the 'real' WARN_ON_ONCE() primitive, as it has no return value, so it cannot be used in conditionals. Fix it. Cc: Daniel Axtens <dja@...ens.net> Cc: Konstantin Khlebnikov <khlebnikov@...dex-team.ru> Cc: Peter Zijlstra <peterz@...radead.org> Cc: Mike Galbraith <efault@....de> Cc: Thomas Gleixner <tglx@...utronix.de> Cc: Linus Torvalds <torvalds@...ux-foundation.org> Cc: linux-kernel@...r.kernel.org Signed-off-by: Ingo Molnar <mingo@...nel.org> --- kernel/sched/sched.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index f2ef759a4cb6..e0329d10bdb8 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -39,9 +39,9 @@ #include "cpuacct.h" #ifdef CONFIG_SCHED_DEBUG -#define SCHED_WARN_ON(x) WARN_ONCE(x, #x) +# define SCHED_WARN_ON(x) WARN_ONCE(x, #x) #else -#define SCHED_WARN_ON(x) ((void)(x)) +# define SCHED_WARN_ON(x) ({ (void)(x), 0; }) #endif struct rq;
Powered by blists - more mailing lists